Occassional thoughts about orienteering
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| okansas.blogspot.com Occassional thoughts about orienteering |
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Sunday, October 10, 2010 Enough to get started with Lidar?OL Laser is a program for creating orienteering basemaps from lidar (aka laser scan) data. I'm far from an expert on either lidar or OL Laser, but I've been playing around with the program and thought I'd write up some notes.I'm impressed with OL Laser and have found it easy to use. I'm sure I've just scratched the surface of what it can be used for. I'm far from being an experienced user. OL laser is useful...but it is written in Swedish. I thought I'd translate bits of the main screen. With the translation and a willingness to experiment (and a bit of lidar data), I think you'll be able to get started even if you don't understand Swedish. You can download OL Laser (click on the "ladda ner" link) Below is the main screen and translations of some of the items on that screen.  The first three buttons are for opening the data: Oppna laserdatafil = open the laser data file Spara laserdatafil = save the laser data file Filinfo = file information The next two buttons are for creating the "GRID or TIN" (a Google search for "lidar and GRID" and "lidar and TIN" should explain the terms): Skapa GRID/TIN = create the GRID/TIN Installningar = settings Next are two blocks of buttons. One is for contours (hojdkurvor) and the other is for images (bilder). I'm going to focus on the image items first: The drop down menu labelled "valj typ av bild" means "select the type of image." There are four options: Laserpunkklass = laser point category Intensitet = intensity Lutning = slope Terrangskuggning = terrain shading You'll see three buttons below the drop down menu: Installningar = settings Skapa bild = create image Spara bild = save image I'm just going to skip over the "hojdkurvor" (i.e. contours) menu and go to the final set of buttons labeled "rita" (i.e. draw). You'll see two boxes you can check: Rita ut kurvor = draw contours Rita ut bild = draw image Installningar = settings That's just barely enough translation that you ought to be able to begin to play around with the program. I'll walk through an example: The first thing you need is some data. If you've got some data, great. If not, you can find some online. One source is the Kansas Data Access and Support Center's collection of lidar. The data are free to download, though you have to register. The most interesting data are the "all returns" files. Once you've got some data, you can open it in OL Laser (use the button at the top of the program screen labeled "oppna laserdatafil" Next, you'll move to the GRID/TIN section of the menu. First, click on the "installningar" (i.e. settings). A new menu opens. Now you've got lots of options and lots of info. It is useful to understand Swedish at this point. I'm not going to translate all the terms. Instead, I'll describe the easiest thing to do to start playing with the data. Look for the checkboxes under "klassificering" (i.e. classification). Make sure the box labeled "mark" (i.e. ground) is checked. Look for the button/boxes just below under "returnummer" (i.e. return number). Make sure "sistareturnen (mark)" is checked. At this point, you've opened the data file and told the program that you're going to create a GRID of the ground. Go back to the main menu and click on "skapa GRID/TIN." It should take a few seconds to create the GRID. At this point, you don't have anything to look at. Go to the "bild" (i.e. image) set of items and select the type of image from the drop down menu. "Terrangskuggning" is a good first choice. Don't worry about the "installningar" just click on "skapa bild." It takes a few seconds to create the image. At this point, you still don't have anything to look at. Go to the "Rita" section of the main menu and click in the box labeled "rita ut bild" (i.e. draw the image) and you should get an image. That's a quick - and rough - intro to OL Laser. You can start to play round with different images and different settings. I've written about my various experiments with lidar. I'm very much self-taught. I'm far from being an expert. I don't really understand all of the technical details of how lidar works or of how best to use the data. But, I've learned enough that I can use the data to generate a useful basemap. Back to okansas.blogspot.com. posted by Michael | 4:18 PM 
Wednesday, August 06, 2008 Lidar - revolution for orienteering mappingI came across some discussion of lidar and orienteering maps on the forum at OPN.NO. Among other things, I learned that they're using lidar as basemap material for at least some of the 2010 World Champs maps. I also learned that in Norway they use the term laser-scanning rather than lidar.Havard Tviete - famous Norwegian orienteer and O' map geek - wrote (roughly translated): For the base to be used for the World Champs in Trondheim we reached the conclusion that 1.25 meter contour interval was good. You want to have as much information as possible but it is also important that the basemap is readable. After checking the basemap in Trondheim, I'm convinced that basemaps from lidar are a revolution for orinteering mapping. The discussion over at OPN.NO includes a link to materials from a O' mapping conference last year. Here's a link to the mapping conference materials. I don't have the time (or energy) to translate, but if you're interested in lidar for O' maps, poke around and you'll find some interesting materials. The image below is from the mapping conference and shows a comparison of the existing orienteering map (5 meter contours) and a lidar basemap (1.25 meter contours). The purple circles show cliffs based on the basemap.  Back to okansas.blogspot.com. posted by Michael | 9:09 PM
Saturday, May 10, 2008 A Swedish comparison of lidar and O' mapsA comparison of a lidar basemap and an orienteering map from Sweden: The image is from Erik Zander's paper on lidar as a method for producing orienteering maps. The paper is in Swedish, but has some nice graphics that compare the data he got from lidar to an orienteering map of the same area. Here is the PDF file. Reading Zander's paper inspired me to play around with some local lidar data. I've been using a free program called Quickgrid to produce contour maps which can be exported and used in OCAD. I also installed a demo version of Global Mapper which seems to have a few more features than Quickgrid (and let me open some lidar data that I can't open in Quickgrid). With Global Mapper I was able to easily view some of the shaded relief lidar data. These files showed a reasonable amount of detail - like ditches and roads - that aren't necessarily visible in the contours alone. I'll keep experimenting...but, now I've got to go do some organizing around the house (and packing). Back to okansas.blogspot.com. posted by Michael | 12:15 PM
Monday, March 24, 2008 Playing with Lidar basemaps I just discovered a bunch of "Lidar" data for the Kansas (aka Kaw) River valley, including Douglas, Jefferson, Wyandotte, and Shawnee counties. So, I figured I'd learn just enough about Lidar to see how hard it'd be to go from data to some sort of basemap. It turned out to be very easy. 1. Scan the discussion at Attackpoint. 2. Scan the front page of Lidar basemaps for orienteering. 3. Download and install the QuickGrid software (a link is at the Lidar basemaps site). 4. Download some data from the Kansas GIS data site. I downloaded 3 square kilometers of Lidar 2006 bare earth for a park not so far from home. 5. Run the data through QuickGrid and you've got a decent looking 2 meter contour interval map (see above...with fancy colors turned on to make the image a little catchier). QuickGrid also lets you export the contours as DXF, which can be opened in OCAD. Without actually going to the terrain to check it out, I can say that the contours look reasonable - certainly a bit better than the standard USGS topo. Judging by the discussion at Attackpoint, there is probably more info one can get from the Lidar data if you're willing to spend the time learning more about it (and have some patience for working with computers and software). Back to okansas.blogspot.com. posted by Michael | 9:00 PM
Sunday, April 25, 2010 Lack of government support?I went for a run on Wednesday. I ran at Clinton Lake. The federal government acquired the land at least 30 years ago. The land is publicly accessible. The federal and state governments have developed facilities - like shelters, restrooms, parking areas. Various organizations - mostly volunteers and non-profits, I'd guess - have built and maintained a great trail network. It is a fantastic resource...provided largely by government support.I ran with an orienteering map. It's a map I fieldchecked. My base map was lidar data. The lidar data provide accurate and detailed contours and planimetric features. I got the lidar data online through the Kansas Data Access and Support Center. State government created that center. A company called Sanborn Mapping created the lidar data. Sanborn was working for a federal agency. The lidar data are all provided at no charge. It is a great deal. From time to time, orienteers complain about a lack of government support for the sport. I think they usually mean that the sport doesn't get a lot of direct public money. But it always strikes me as too narrow a view. Orienteering gets lots of government support, as the example of last Wednesday's run illustrates. I think it is just human nature to see barriers before (or instead of) opportunities and to take advantages as givens. I like to think that if we could change how we viewed our own situations, we'd be better able to take advantage of those opportunities. If only human nature didn't stand in the way! Back to okansas.blogspot.com. posted by Michael | 10:42 AM
Saturday, August 01, 2009 Mapping near the center of the Earth I took the first tentative steps toward a new mapping project. I put together 1 meter Lidar contours and the Lidar intensity images. I may use this as a base map. The Google Earth image of the area is below.  The area is a small section of the West Campus of the University of Kansas. It has a mix of built up area, forest, sports fields and parking areas. My plan is to create a 1:5,000 sprint map which can be extended to the north and west as time permits. The Google Earth image and the Lidar intensity image clearly show some new construction - new roads and parking lots. I'll have to poke around and see if I can find some newer photos that include more of the new construction. In comparing the Lidar and the photo I noticed an L-shaped section of forest that shows up as missing contours on the Lidar contours (on the west side of the map, right in the middle). I'm guessing the area is very dense cedars. West Campus Trivia West Campus is the place I first orienteered, way back in 1980. The event was on a black and white map. We started near the pond and made a clockwise loop. The course went a bit north of the map bit that I've posted above. I can't remember the control locations, but I remember the general shape of the course. Google Earth Trivia Did you know that Lawrence is the center of Google Earth? Open Google Earth and zoom in and you'll end up at a point about 1 km north of the map I posted above. That's the same apartment complex that Peggy lived at when she first studied at KU. Back to okansas.blogspot.com. posted by Michael | 4:24 PM
Monday, June 11, 2012 A modest lidar-based orienteering training map
If you're interested in how lidar (aka laser scan) data can be used to generate orienteering maps, you need to be checking out what's going on over at RouteGadget.
I don't have the computer skills to do as much, but I'm learning. I spent some time this weekend looking at some very interesting terrain and creating a map with OL Laser. I thought I'd share what I've been doing.
From the lidar data - which I was able to find and download for free - I generated 2.5 meter contours. I also generated an "intensity" image based on the ground. From the intensity image I was able to pick out roads, trails and parking areas. I could also make out vegetation from the intensity image (which is something like a black and white photo). But, I decided to use the vegetation data in the lidar to generate vegetation information.
To create a rough vegetation map, I used OL Laser's object height feature. For anything below 0.8 meters, I created a light yellow shade. For everything above 0.8 meters, I created white areas (to correspond to forested areas).
You can see the results below.
 I'm guessing the forest might be a little bit thick, so I also created a version where I shaded objects above 0.8 meters with light green.  You can see an air photo of the area below and see how it matches up. To provide some context, the area shown is about 1.5 km from east to west.  I haven't been to this terrain. It certainly looks very interesting. I think it must be some sort of sand terrain. I expect that I'll know more once I've had a chance to see it in person. One thing I haven't done (and that's just because I've been lazy), is use the latest version of OL Laser. I need to get my act together and download the latest version. Back to okansas.blogspot.com. posted by Michael | 8:21 PM
Saturday, October 10, 2009 Some Lidar data from one of my current mapping projectsI discovered another program for using Lidar data. Microdem has a feature that I've made use of. I can take a "DEM" file and create an image that lets me see quite a lot of the detail.Below is an area that I've started mapping. What is especially useful is that I can pick out the bottom of small ditches and streams. The bottom of the image - what looks like a fuzzy television picture - is some sort of error. I haven't figured out what is going on. The DEM data covers that part of the terrain, but for some reason I can't get Microdem to show it.  Below are contours (2 meter) generated from the Lidar bare earth data. I added the trails by running the area with a GPS and then using the track to draw the trails. It isn't perfect, but it is a good start.  I also use the Lidar "intensity" data to pick out some detail. For the most part I use the intensity data to pick up vegetation - individual trees and vegetation boundaries. Sometimes I'm able to pick out subtle vegetation information. I think there is the potential to get a lot more information out of the intensity image than I've managed to get.  Back to okansas.blogspot.com. posted by Michael | 6:59 PM
Saturday, December 27, 2008 Comparing Lidar base to the old O' mapHere is a comparison of the old orienteering map and the Lidar map I wrote about yesterday. We fieldchecked the old map a long time ago (1988-89, I think). The basemap we used was from the US Corps of Engineers. My memory is that it had 10 foot contour intervals. The quality was good.  For anyone interested in Lidar, I would encourage you to download a couple of the free software tools that let you look at the data (Quickgrid and Global Mapper are the ones I've used), find some data, and see what you can do. I don't know much about finding data, but there is plenty of free data to download at the Kansas geodatabase catalog (look for bare earth data under "elevation" and use it to make contours in Quickgrid). Here is everything I've written about Lidar. Back to okansas.blogspot.com. posted by Michael | 9:41 AM
Friday, December 26, 2008 An experiment with a Lidar basemapHere is a low effort/high tech basemap I put together yesterday. I downloaded Lidar bare earth data and created the contours at 2.5 meter contour interval. I ran the trails wearing a little GPS and put in the trails from the GPS. I used Lidar-based DEMs (digital elevation models?) to get the stream beds (an example below shows a bit of the DEM).  I described this as a low effort/high tech basemap. Low effort means not a lot of time. Downloading and converting the Lidar contours took maybe 20 minutes. Exploring the area with the GPS and taking a few notes took maybe 80-90 minutes (the area is 1K). I put in about 45 minutes of time drafting (mainly the trails and adding the stream beds). If you're familiar with local O' maps, you should recognize the map as part of the old Rockcrusher map on the south shore of Clinton Lake. Back to okansas.blogspot.com. posted by Michael | 11:24 AM
Thursday, April 03, 2008 More Lidar... Oh yeah, that's "unsharp-masked filtered (high-pass) data. That is, the slowly varying elevation is removed and sharp features are enhanced...., so you can see buildings and trees in that one." The image came to me in my email from an orienteer who downloaded some of the Kansas Lidar data and did some magic to the raw data. I know very little about computers and much less about Lidar data. But, I think I might try to learn a bit more. After a few more minutes poking around the internet to learn about Lidar, I discovered how easy it is to create a contour map at 1 meter interval. The example below is an area near Perry Lake (north of Lawrence). It shows a lot of contour detail in the major reentrants. I'm guessing (hoping) that is shows enough detail to easily fieldcheck the stream bed.  Back to okansas.blogspot.com. posted by Michael | 7:50 PM
Saturday, March 29, 2008 More lidar map dataI spent some time this morning looking at Lidar data available for the area and discovered something called "intensity." I don't really know what that means, but I discovered that the Lidar intensity data looks a lot like an aerial photograph.Here is the intensity data for a part of Lawrence and the University of Kansas campus:  Here is the sprint orienteering map of the campus:  You can easily pick out a lot of detail from the instensity data. It certainly looks - to me - like Lidar data is going to be quite useful for basemaps...as soon as it becomes more widely available. Back to okansas.blogspot.com. posted by Michael | 5:35 PM
Monday, June 18, 2012 Nice terrain in North DakotaI spent some time exploring the terrain I wrote about last week and I was not disappointed. The terrain is interesting and runnable (even with summer vegetation).You can see a GoPro chest-cam video with a GPS track and map to get an idea of the area. The map I'd created from lidar data and OL Laser turned out to be quite good. The main changes that it would need to be a really good map would be adding slope tags to help an orienteer distinguish depressions from hills, add the small trails, improve the vegetation detail, and add the occasional fence lines and power lines. It would be tedious, but not difficult, to add the slope lines based on the lidar data. The vegetation could be improved by using green circles to indicate the distinct lone tress that show up in the current map and adding some distinct vegetation boundaries for the edges of the larger stands of trees. I think I could do a pretty good job by comparing the lidar data to Google earth images. Getting the small trails consistent and accurate would take a mix of studying air photos and spending some time in the terrain. Getting the fence lines correct would take a visit to the terrain. You might be able to get some of the fence and power lines sketched in from air photos. The Bing Maps photo has a lot of detail. It might be worth adding some marshy ground. When I ran around the area I didn't get my feet wet, but I saw a couple of areas that looked like they'd be marshy during part of the year. The biggest problem with the area is where it is - North Dakota. As best I can tell there aren't any orienteering maps or orienteers in North Dakota. Back to okansas.blogspot.com. posted by Michael | 7:51 PM
Friday, September 03, 2010 More lidar experimentsI spent some time today playing around with lidar data and trying to learn how to get more out of it than just contours. Here are three images based on the "all returns" data from an area nearby. If you're familiar with Lawrence, you'll recognize McCollum Hall in the top left of the images.   For my previous lidar experiments, I've generated contours and used the intensity files (which is basically a fuzzy, black and white air photo). I think using the all-returns data gives me access to a lot more information. Back to okansas.blogspot.com. posted by Michael | 8:07 PM
Monday, April 07, 2008 More Lidar - University of Kansas CampusEddie has been playing around with the Lidar data that covers the University of Kansas campus. This is one of the images he created. It is pretty easy to match up the orienteering map with the Lidar image from Eddie (look for the football stadium and the big hill). Basketball fans might like to know that one of the big buildings at the front of Eddie's image is Phog Allen Fieldhouse....Home of the 2008 NCAA men's basketball national champions!!!!! Back to okansas.blogspot.com. posted by Michael | 7:53 PM
Wednesday, June 13, 2012 More fun with lidar and vegetation
Lidar data includes information on "density" of objects. While I'm not exactly sure what that means, I think it gives information that can help understand how thick a forested area might be. The map below shows an image where I've used different shades of green to identify regions of different object density. The darkest green areas are areas of higher object density. The white areas are areas of the lowest density.
 To get this image, I used OL Laser to assign the shades to different object densities and I excluded any points that were within one meter of the ground. My previous experiments with trying to map runnability were based on object heights. Those experiments were moderately successful. I was able to use the information to help understand runnability. But I still had to do a lot of interpretation in the field and make a lot of changes. I'm hoping that the density information will be more precise, requiring fewer changes. I'm looking forward to comparing the map above with the actual terrain and see how well the density data maps vegetation. Back to okansas.blogspot.com. posted by Michael | 8:53 PM
Saturday, February 25, 2012 Lidar data for vegetation mappingI've written about my experiments in using lidar data and OL Laser to generate rough maps of runnability. Here is a screen cast that demonstrates how I create the images.Back to okansas.blogspot.com. posted by Michael | 10:32 AM
Sunday, December 04, 2011 Mapping runnability with lidarI've been experimenting with trying to map vegetation - the runnability of the forest - from laser scan/lidar data.The map below shows one of my tests. I created the map using OL Laser. I used the software to measure object heights. I created different colors to correspond to object heights. The yellow is ground height. In this particular map, the yellow areas are mostly open fields or open water. Then I created three other categories of object height. The lowest objects are shaded dark green. Medium height objects are light green. The heighest objects are white. I figured this shading scheme would roughly match runnability.  The map below shows highlights three different sections of forest. Section A is an area that has a lot of low objects, with some yellow areas mixed in. This area turns out to be dense cedar trees. It would be mapped dark green on the final orienteering map. Section B is an area with mainly tall objects. In this case, the tall objects are mature trees. The area has little undergrowth and would be mapped as white forest. Section C is an area that is mixed. It doesn't have as many short (dark green) objects as A and it doesn't have as many tall (white) objects as B. This area would probably be a shade of green on the final orienteering map.  The tricky thing about mapping the runnability of the forest around here is that the changes are generally subtle. The shift from white woods to light green woods isn't very distinct and deciding where the mark the change is difficult for the mapper. The laser scan data might be a way to help see some of those distinctions. I plan to do some more experimentation. Back to okansas.blogspot.com. posted by Michael | 9:01 AM
Monday, November 21, 2011 Comparing the map and the lidar dataHere's a comparison of the current orienteering map and some laser scan (aka lidar) data of the same area. First, take a look at the current orienteering map with 5 meter contours.
I'm not sure of the source of the contours. I think it might be USGS "DEM" (I think DEM = digital elevation model).
Now, take a look at the laser scan contours. The countours are drawn at 2.5 meters (with a little bit of smoothing). I think you'll notice that these contours are a bit more detailed.
 Finally, take a look at the laser scan "slope" image. In the slope image, the steeper the slope, the darker the shade. The slope image is especially useful for picking out the earth banks along streams and erosion features. In this area, you can also see some of the older trails (look for the trail that runs parallel and just to the east of the road on the top of the hill).  I used OL Laser to generate the contours and the slope image. I'm a fan of OL Laser. I find it fairly easy to use and I'm able to get a lot of information out of the laser scan data without a lot of work. Back to okansas.blogspot.com. posted by Michael | 7:17 PM
Thursday, December 30, 2010 Looking at some lidar data The image shows a bit of the basemap for an orienteering map I've been working on. I prepared the basemap from laser scan (lidar) data that I got for free. I used OL Laser to create a "lutning" image. The "lutning" image seems to be the best base material for this sort of forest.The circles show some of the features that I can pick up from the data and that I show in the video below. The dashed line is a very subtle linear feature. It is the remnants of an abandoned trail. Looking at the basemap at Rockcrusher from okansas on Vimeo. Latest from Attackpoint A new version of the video + GPS tracking at Attackpoint that combines the video with an QuickRoute orineteering map. Very, very cool. Back to okansas.blogspot.com. posted by Michael | 5:30 PM
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